The present invention relates to a battery-operated screwdriver, and also to a charger shell for a battery-operated screwdriver.
Battery-operated screwdrivers are already available in the 2.4V to 3.6V power class, as known for instance from European Patent Disclosure EP 1 066 930. They usually have NiCd cells as energy-storing means, an ON/OFF switch with a short switch button, and without continuously variable speed governing they have both a switch for switchover from counterclockwise to clockwise operation, a gear, in particular a planetary gear, that steps the motor rpm down, and a motor with a standard diameter of 27.5 mm. There are rodlike and pistol-shaped versions as well as versions with a grip whose angle can be adjusted. For charging, these devices are either connected to a charger via a plug—in the manner of a cell phone or electric shaver—or are connected to contacts via a mount into which the device is placed. The mounts can be secured to a wall, for instance, to make handling for charging simpler.
For that purpose, the charging mode must be brought about for both the charger and the electrical connection, but this does not happen automatically after every use. As a result, the device is often not ready for use precisely when it is needed, and the familiar memory effect for conventional NiCd batteries is another disadvantage. After a certain amount of time of not outputting power, NiCd batteries discharge, and so battery-operated screwdrivers equipped with them discharge partially after a short time even when not used. If they are put in the charging mode when they are partially discharged, then after charging, because of the memory effect, only the difference from the newly charged quantity—and hence reduced power—is available.
Another disadvantage of the known battery-operated screwdrivers is the limited availability of screwdriver bits and various tool inserts.